1. Field of the Invention
This invention relates to an electromagnetic directional control valve capable of changing over flow paths of fluid to three different positions and, more particularly to a compact electromagnetic directional control valve which can be housed in a tubular member having a relatively small size such as a piston rod.
2. Description of the Prior Art
A prior electromagnetic directional control valve as disclosed in the Utility Model Public Disclosure (KOKAI) No. 115468/82 for example, was constituted from a plurality of solenoid units (hereinafter referred to as electromagnetic means) arranged coaxially, one movable valve body moved by these electromagnetic means and at least two springs for directly supporting the movable valve body on both ends.
Thus, a force for stopping the movable valve body stationarily at a certain position is determined by the spring constant composed of the two springs. Hence, in the prior electromagnetic control valve, it was necessary to enlarge the spring constant composed of the two springs for stabilizing stationarily the movable valve body even when an external force, for example vibration, was applied in the direction of moving the movable valve body.
However, when the spring constant is enlarged, problems are encountered that when the movable valve body is moved against these springs, a large suction force is required to be produced by the electromagnetic means, resulting in the increase of electric power consumption of the electromagnetic means and the provision of a large-sized electromagnetic means.